SSG5 ALG monitoring via SNMP

get alg sip calls Total number of calls = 0 (# of call legs 0)-----------------------------

Is there a MIB that I can use to monitor this via SNMP? I'm looking for something that would tell me current/max. So if there are 16 current calls and 64 is the max I need 16/64 returned. Even if it takes 2 different commands to get the information. I can't seem to find it and it would be very useful for us. Thanks in advance!